1. Field
The disclosed concept relates generally to electrical systems and, more particularly, to aerospace electrical systems, such as, for example, power distribution units. The disclosed concept also relates to circuit protection modules for electrical systems. The disclosed concept further relates to electrical switching apparatus such as, for example, circuit breakers for electrical systems.
2. Background Information
Aircraft or aerospace electrical systems generate, regulate and/or distribute power throughout an aircraft.
Aerospace power distribution units (PDUs), for example, generally include an enclosure, a number of input and output connectors, internal electrical bussing, electrical conductors, a number of electrical switching apparatus, such as contactors, circuit breakers, relays and the like and/or fuses. More specifically, in aircraft or aerospace electrical systems relatively small circuit breakers, commonly referred to as subminiature or aircraft circuit breakers, are often used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition. Aircraft circuit breakers also often serve as switches for turning equipment on and off, and are grouped together as part of a circuit protection module with the circuit breakers/switches being accessible on an outer panel of the enclosure, within the aircraft.
The housing of such circuit breakers is typically made of melamine or a suitable thermoset compound to provide dielectric insulation and suitably isolate the electrical components. However, significant heat is generated within the circuit breaker housing, which increases resistivity and adversely affects system performance. For example, it is generally well known that the separable electrical contacts enclosed within the housing account for up to 75% or more of the heat within most aerospace electrical systems. The melamine or thermoset material of the circuit breaker housing is an effective electrical insulator, but it is thermally insulative and, therefore, retains heat within the circuit breaker and prevents good heat transfer to free air or the aircraft structure.
There is room for improvement in electrical systems, and in circuit protection modules and electrical switching apparatus therefor.